Mashed potatoes

I add a little cream cheese and, I know it sounds a little weird, garlic salt.

When you heat the milk, you can add a smashed clove of garlic and a sprig of thyme and a bay leaf. Strain these out before adding the milk to your mashed potatoes, and you'll add some nice subtle flavor.

I've also used brown butter instead of regular melted butter, and that was delicious. And one year I added little bits of seared kielbasa to the mashed potatoes.

What a fun question—there are oh-so many ways to make mashed potatoes sing. If you want to stick to classic ingredients, you might experiment with a new technique, like the one outlined here: https://food52.com/blog/16854-a-genius-trick-for-more-buttery-tasting-mashed-potatoes
It's pretty simple, but our resident Genius Kristen Miglore gave it a thumbs-up, and I'd take any recommendation from her seriously!
And then of course there are all the delicious add-ins to consider: chives, sour cream, cheese, bacon, caramelized onions...we once did a recipe contest that might inspire you: https://food52.com/contests/110-your-best-mashed-potatoes
Hope you have a great Thanksgiving!